An electrophotographic type image forming device generally includes a photosensitive drum, a charge unit, an LED array, and a developing unit. The charge unit is adapted for uniformly charging a surface of the photosensitive drum. The LED array is adapted for forming an electrostatic latent image on the charged surface of the photosensitive drum. The developing unit is adapted for forming a visible developer agent image with charged developer agent at the electrostatic latent image. The visible image is then transferred onto an image recording medium such as a sheet fed from a sheet cassette, so that the visible image can be formed on the sheet.
In such a conventional image forming device, a process cartridge is detachably provided to a frame of the device. The process cartridge accommodates therein the photosensitive drum, the charge unit, and the developing unit. The process cartridge can be exchanged with a new process cartridge upon consumption of developer agent or upon degradation of the photosensitive drum. In order to perform such exchange, one of the photosensitive drum, the charge unit and the developing unit may be mechanically interfered with the LED array. Such interference may occur easily in a front access type image forming device in which the frame has a front side provided with a cover, and the process cartridge can be detached from the frame through a front opening after opening the cover.
In order to avoid such mechanical interference, a link mechanism has been proposed that retracts an LED array to a non-interference position with respect to the process cartridge when a door is open. This structure can facilitate removal of the process cartridge from the frame.
However, operating position of the LED array may be varied in accordance with a repeated retracting movement thereof, which degrades imaging quality. Instead of moving the LED array, the latent image is maintained stationary whereas the process cartridge is moved for its detachment and attachment away from the LED array. However, in the latter case, a sheet feed mechanism and the sheet cassette may become an obstacle for the moving the process cartridge away from the LED array.
That is, the sheet cassette and the sheet feed mechanism for feeding the sheet from the sheet cassette are generally disposed at a lower portion of the frame and below the process cartridge. On the other hand, the LED array is disposed at an upper portion of the frame and above the process cartridge. Therefore, the process cartridge may be mechanically interfered with the sheet feed mechanism and the sheet cassette by the movement of the process cartridge in a direction away from the LED array.